The igniter in the rocket motor is used to give sustained combustion to the propellant. This research paper focused on experimental and numerical investigation of effect of the igniter mass on the maximum pressure rise in single grain solid propellant rocket motor. Experiments are carried out with varying igniter mass by approximately ±15 % of calculated igniter mass. The experimental results are in good agreement and compared with numerical results. A linear relationship between igniter mass and maximum pressure is also established numerically. The present investigation reveals that, the igniter mass contributes in maximum pressure rise along with propellant. The maximum pressure can be retained within required range by optimizing the igniter mass for safe working with rocket motor.

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　Ammonium nitrate is the most consumed chemical fertilizer in agricultural fields. Due to its easy accessibility and economic value, its physicochemical properties are also utilized in the explosive industry. However, this feature has made it preferable for anti-social purposes. To prevent this, researchers have focused on the addition of various chemicals to reduce the enthalpy of ammonium nitrate to the production process of ammonium nitrate. 　In this study, the most important parameter of ammonium nitrate for the plant to reduce nitrogen concentration and storage conditions to minimize the triggering of caking phenomena and does not affect the heavy metal uptake of the plant by adding diboron trioxide, potassium fluoride and potassium tetrafluoroborate, enthalpy value, with significantly reduced results, calorimetry tests was also supported. 　As determined from the results of instrumental analysis, it was observed that ammonium nitrate significantly increased in the crushing strength even when diboron trioxide, potassium fluoride and potassium tetra fluoroborate, which were used during the study, were added (<0.03 %). It can be stated with the results obtained in this case that the tendency of ammonium nitrate to be degraded decreases and its storage life increases. Although the crushing strengths are similar to each other when all three chemicals are added alone, it was found that when all three chemicals are added to the same reaction medium, it has the highest crushing strength. 　However, due to the low concentrations of boron content, which is a heavy metal of the chemicals used, it can be seen from the peak heights in the ammonium nitrate content in anion and cation analysis in ion chromatography. In this respect, the nitrogen concentration of ammonium nitrate is not affected in terms of agricultural use, as can be seen in nitrogen analysis. When DSC analysis was performed as calorimetric value, it was found that boron compounds had a significant effect on reducing the enthalpy of ammonium nitrate. Thus, it was found that with the addition of all three chemicals, there was no exothermic peak in combustion reactions, so the tendency to detonate was significantly reduced. In order to analyze another parameter affecting the detonation reaction, surface porosity analysis was performed with an electron microscope. It has been found that boron compounds reduce surface porosity, thereby reducing detonation enthalpy, however, on the surface of the ammonium nitrate, where all three compounds are added together, the smallest and least number of porosity is obtained compared to the ammonium nitrate surface, where each compound is added alone.

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The ignition and safety characteristics of a radio frequency (RF) insensitive semiconductor bridge (SCB) was presented. Firstly, the influence of resistance of negative temperature coefficient (NTC) thermistor on SCB ignition performance was studied by a capacitor discharge unit. Secondly, the constant current firing set and an infrared temperature measurement system were utilized to study the temperature change of the SCB with different NTC thermistor. The results showed that as the resistance of the NTC thermistor increased, its effect on the ignition and safety characteristics of SCB became weaker. NTC with a resistance of 10 Ω succeeded in protecting SCB initiators against electromagnetic environment without affecting their performance.

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The objective of this research article is to carry out the shelf life extension study of imported main seat ejection cartridges for trainer aircraft application. The deterioration of various chemical compositions and its properties takes place for the propellants inside the ejection cartridges over a time, even at ambient storage conditions. Life extension is a methodology/technique to assess an impact of environment and induced stresses as per selected methods. Internal ballistics parameters like maximum pressure, time to half maximum pressure, and corresponding time to maximum pressure are generated by firing these cartridges in a Vented Vessel (VV). A VV is designed and fabricated for evaluating and recording these parameters. These parameters are measured using Data Acquisition System (DAS). Experiments are performed to assess the remaining useful life in terms of internal ballistic performance parameters and accordingly extended the shelf life of seat ejection cartridges. The statistical analysis of these performance parameters are evaluated after subjecting to Highly Accelerated Life Trials (HALT). The trial results show that performance parameters are more consistent in cold conditions than in hot conditions. Further, the maximum pressure is higher in cold condition than in hot condition. This is attributed to unpredictable behaviour of the propellant in Original Equipment Manufacturer (OEM) cartridge. After statistical analysis, it is observed that the spread in standard deviation in Phase I at hot and cold conditions are smaller than that of Phase II. This research article describes about the shelf life extension methodology of imported main seat ejection cartridges to enhance the shelf life for aircraft application. This kind of study is essential and helps to keep the entire aircraft fleet in operational readiness. Considering the overall performance of imported main seat ejection cartridges in hot and cold conditions, the maximum pressure (P_max) varies from 9.70 to 10.91 MPa, time to 1/2 P_max varies from 730.70 to 790.00 ms and time to P_max varies from 245.58 to 269.25 ms.

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Ultrafine RDX (cyclotrimethylene trinitramine, C₃H₆N₆O₆) particles were prepared by ultrasonic assisted spray method, and the RDX-based composites with various polymer binders were obtained by water suspension method. The binders in composites are as follows: ACM (AR-12, AR-14, AR-71), Viton A and F2602. The binding energies between crystal surfaces of RDX and the binders were calculated, which show that the binding energies of RDX and ACM are higher than those of RDX and other binders. Then the crystal morphologies, crystal structures, thermal decomposition properties and mechanical sensitivities of raw RDX, ultrafine RDX and the RDX-based composites were characterized. Finally, the static mechanical properties of the RDX-based composites were tested and the detonation pressures of samples was calculated. The results show that there are different degrees of improvement in the combination properties of RDX after coating by the polymers, and AR-71 is the most suitable binder for coating RDX.

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